A Laboratory Investigation of the Effect of Temperature on Densities and Viscosities of Un-conventional Fuel (Residual Fuel Oil) and Petroleum Diesel Oil.

Fuel properties such as viscosity and density play a critical role in determining the efficiency, performance, and environmental footprint of combustion systems, particularly in industrial and power generation applications. Understanding how these properties respond to temperature variations is essential for optimizing fuel handling, atomization, and combustion, especially when considering the use of unconventional fuels such as Residual Fuel Oil (RFO). This study investigated the effect of temperature on the viscosity and density of RFO compared with conventional petroleum diesel. Fuel samples were analyzed in a controlled laboratory environment using a digital rotational viscometer and ASTM-compliant hydrometer across a temperature range of 20°C to 100°C, at 10°C intervals. Measurements were replicated and subjected to regression modeling. The results revealed that both viscosity and density decrease as temperature increases, with viscosity exhibiting an exponential decline and density showing a nearly linear trend. RFO demonstrated significantly higher viscosity than diesel at all temperatures, indicating the necessity of preheating for proper flow and combustion. Statistical analysis confirmed the differences in thermal behavior were significant. These findings have important implications for energy systems considering fuel switching or dual-fuel operations, as they highlight the need for thermal management strategies when using heavier fuels like RFO. The study contributes valuable data for the design and operation of systems that aim to integrate unconventional fuels into existing diesel infrastructure while maintaining efficiency and compliance with emission standards.